The invention relates to the treatment of wood with pentachlorophenol.
Wood used as a construction material is subject to decay and attack by fungus, termites and various beetles. For that reason, it is necessary to apply a preservative to many wood products, such as lumber, utility poles and railroad ties.
In many of the commercial plants in which a preservative is applied to wood, the substance used is creosote. Creosote has a strong and unpleasant odor, and wood which has been treated with creosote not only is unpleasant to handle but also has an unsightly appearance. The uses of wood which has been impregnated with creosote are limited also because most paints cannot be effectively applied to creosote-impregnated wood.
Pentachlorophenol is less expensive than creosote, and is at least as effective as a fungicide. However, pentachlorophenol has not been used as extensively as creosote in the treatment of wood, because it has been necessary heretofore to apply pentachlorophenol in an organic solvent, which greatly increases the cost.
The solvents commonly used in the impregnation of wood with pentachlorophenol are heavy oils such as no. 2 heating oil.
Wood also can be treated by impregnating with a solution of pentachlorophenol in a volatile solvent, and then evaporating the solvent, but the necessity of recovering the evaporated solvent further increases the cost.
The amount of oil consumed in treating wood during 1976 in the United States was about 200 million gallons.